1. Field of the Invention
The present invention relates generally to a method of performing a layer operation in a communications network.
2. Description of the Related Art
A cellular communications network typically includes a variety of communication nodes coupled by wireless or wired connections and accessed through different types of communications channels. Each of the communication nodes includes a protocol stack that processes the data transmitted and received over the communications channels. Depending on the type of communications system, the operation and configuration of the various communication nodes can differ and are often referred to by different names. Such communications systems include, for example, a Code Division Multiple Access 2000 (CDMA2000) system and Universal Mobile Telecommunications System (UMTS).
UMTS is a wireless telephony standard which describes a set of protocol standards. For example, UMTS sets forth the protocol standards for the transmission of voice and data between a base station (BS) and a mobile or user equipment (UE). The UMTS is divided into a plurality of layers. Layer-1 protocols handle digital radio transmission (e.g., encoding data packets for transmission, decoding received data packets, forward error correction, etc.). Layer-2 protocols (e.g., radio link control (RLC)) handle data packet operations such as data packet fragmentation and reassembly, error detection and retransmission, scheduling data packet delivery, etc. Layer-3 protocols include end-to-end protocols (e.g., IP, TCP, UDP, RTP, etc.). The layer numbers denote a layer hierarchy where lower layer numbers indicate lower layers relative to higher layer numbers, and vice versa.
However, the layers do not necessarily communicate with each other. In other words, information determined at a given layer or extracted from operations at a given layer is typically unavailable at other layers. Also, with regard to the transmission of data packets, layers do not examine data packet contents received from upper layers, instead performing layer specific operations (e.g., encapsulation) and passing the data packets to a lower layer.